1. Field of the Invention
The present invention relates to a fastening method, a fastening system, and a bolt used therefor.
2. Description of the Related Art
In manufacturing an automobile, after a bracket is assembled to an engine body and is formed with a camshaft hole, the bracket is detached and a camshaft is mounted and then, the bracket is again assembled and the camshaft is interposed between the bracket and the engine body. The bracket and the engine body are fastened by a bolt.
In the case of a crankshaft, a lower end of a connecting rod is divided into two, and the crankshaft is sandwiched between the two divided portions and the two divided portions are fastened by a bolt and are mounted.
When two members, such as the engine body and the bracket or the two divided portions of the connecting rod, are fastened by a bolt as described above, a method shown in FIG. 8 is conventionally used. FIG. 8 shows a case in which to-be-fastened members a and b are fastened by a bolt c. A problem which is caused during a fastening operation is that it is necessary to secure a clearance for inserting the bolt between an outer peripheral surface of a shank of the bolt c and an inner peripheral surface of an insertion hole e of the to-be-fastened member a and, therefore, the insertion hole e of member a and a threaded hole f of member b are brought into misalignment during fastening and a predetermined connection accuracy can not be obtained. Therefore, in the case of the camshaft and the like, this misalignment causes friction and/or noise.
Thereupon, in the conventional method, a pressure ring g is fitted into an annular groove h formed around the threaded hole f of member b, and an annular groove i formed around the insertion hole e of member a is press-fitted over the pressure ring g, thereby providing an accurate connection between a and b.
However, mounting the pressure ring g, which is an additional part, and forming the grooves h and i complicate the manufacturing process and the structure, which increases costs and lowers productivity. Further, it is necessary to provide a space for mounting the pressure ring g, which makes it difficult to reduce the size of the parts.